With increased functionality of vehicles in recent years, various rotation angle detection devices have been developed to detect the amount by which the brake pedal is depressed or the rotation angle of the pedal, thereby providing a variety of controls. One such conventional rotation angle detection device will now be described with reference to FIGS. 8 to 10.
FIGS. 8 and 9 are a sectional view and an exploded perspective view, respectively, of conventional rotation angle detection device 11. Rotation angle detection device 11 includes case 1, rotor 2, lever 3, spring 5, magnet 6, wiring board 7, magnetic sensing element 8, approximately L-shaped terminals 9, and cover 10. Case 1, rotor 2, lever 3, and cover 10 are made of an insulating resin. Spring 5 is made of steel wire and wound like a coil.
Case 1 is cylindrical and has cylindrical part 1A at a center thereof. Cylindrical part 1A is connected to an inner peripheral edge of intermediate part 1C, and an outer peripheral edge of intermediate part 1C is connected to exterior wall 1D. Rotor 2 is rotatably inserted into cylindrical part 1A and flange 2A formed on rotor 2 is in contact with intermediate part 1C.
Lever 3 is fastened with screw 4 to rotor 2. Spring 5 is placed in a slightly twisted state between lever 3 and intermediate part 1C. Spring 5 is engaged at one end with lever 3 and at the other end with intermediate part 1C. In this state, spring 5 pushes lever 3 in such a manner that lever 3 is positioned at a predetermined angle with respect to case 1.
Magnet 6 is substantially cylindrical and is fixedly attached to the center at the end of rotor 2 by, for example, insert molding. On wiring board 7, magnetic sensing element 8 such as a hall element is mounted so as to face magnet 6 with a predetermined gap therebetween. Wiring board 7 is provided on both sides with a plurality of wiring patterns (not shown).
Terminals 9 are implanted on case 1 by, for example, insert molding. Each of terminals 9 is connected to magnetic sensing element 8 via the wiring patterns at one end, and is extended to rectangular-column-shaped connector part 1B at the other end. Cover 10 is fastened to case 1 and covers the opening of case 1, wiring board 7, and other components.
Rotation angle detection device 11 thus structured is equipped in the vicinity of rotation shaft 55A of brake pedal 55 of a vehicle as shown in FIG. 10. Lever 3 is attached to actuating pin 55B, and magnetic sensing element 8 is connected to the electronic circuit (not shown) of the vehicle via terminals 9 and lead wires (not shown).
In the above-described structure, when the driver depresses brake pedal 55, arm 55C rotates about rotation shaft 55A as a fulcrum, and actuating pin 55B makes lever 3 rotate. These rotations allow rotor 2 to rotate while twisting spring 5, thereby rotating magnet 6 attached to rotor 2. This changes the direction of the magnetic field flowing from magnet 6 to magnetic sensing element 8, and hence, changes the magnetic field strength applied to magnetic sensing element 8. Element 8 detects this magnetic field strength. The electronic circuit calculates the rotation angle of rotor 2, that is, the stroke length of brake pedal 55 from the magnetic field strength detected by magnetic sensing element 8. The vehicle is variously controlled according to the stroke length (refer to Patent Literature 1, for example).